Aim: The impact of HLA sensitization from blood products in the pre-hematopoietic stem cell transplantation (HCT) period has not been well characterized to our knowledge. This retrospective study was aimed to compare the HLA sensitization levels pre- and post-red blood cell (RBC) and platelet (PLT) transfusions in adult pre-HCT patients.
Method: Adult patients who received allogeneic HCT between 1/1/2018 and 12/31/2023 at Stanford Health Care were included in the study. Pre-HCT HLA IgG antibody screen testing was performed using single antigen bead assay. All transfusion products were pre-storage leukoreduced. Patients with history of hematologic malignancy and those on the HCT list additionally received irradiated products. The HLA antibody test results and transfusion products data were retrieved. Patients with both pre-transfusion and post-transfusion serum samples (>=14 days from last transfusion) were included. The class I and II HLA antibody cPRA changes between the post- and pre-transfusion samples were calculated.
Results: A total of 1499 HCT patients were identified and 385 patients had transfusion records at our institution. Of the patients with transfusions, 315 patients met the inclusion criteria, among whom 237 received both RBC and PLT transfusions, 50 received only RBC transfusions, and 28 received only PLT transfusions. Of the patients receiving both RBC and PLT transfusions, 39% and 64% had no change, 37% and 18% had a decrease, 24% and 18% had an increase of cPRA values for HLA Class I and II, respectively. Of the patients who received only RBC transfusions, 56% and 70% had no change, 30% and 12% had a decrease, 14% and 18% had an increase of cPRA values for HLA Class I and II, respectively. For the patients who received only PLT transfusions, 54% and 64% had no change, 43% and 29% had a decrease, 4% and 7% had an increase of cPRA values for HLA Class I and II, respectively. (Table 1) The median duration between most recent transfusion and the last post-transfusion HLA testing was 131 days, 91 and 115 days for RBC and PLT, RBC alone, PLT alone, respectively.
Conclusion: In this single center study, blood product transfusion did not increase HLA sensitization in majority of pre-HCT patients. In a minor subset of patients, HLA sensitization increased post-transfusion which could pose challenges in HCT donor selection.
